feat: v1.8.1 — copy-ready stage-handoff block at every skill's finish

[genkovich]

What

Every skill now ends by emitting a copy-ready handoff block instead of a bare «Next: …» line. Canonical format in new skills/_shared/handoff.md; each skill keeps a one-line pointer + supplies its own content.

The block (sectioned):

## ✅ <skill> — <slug>

**What I did**
- <artifacts produced + the commit proposed>

**Review before continuing**
- `docs/features/<slug>/<file>` — <what to check>

**Run next**
1. `/clear` — mandatory (fresh context; the next stage re-reads from disk)
2. then run:

/sdd-

↳ or `/sdd-<alt> <slug>` to <skip>   ← only when a real skip exists

Fixes the complaint that the per-gate output was poor and hard to copy/verify: you now see what changed, which files to open at this gate (real paths), and what to run next (/clear + a fenced, one-click-copy /sdd-… command) without scrolling back.

Variants

• Backbone forward (survey → … → ship): /clear mandatory + next stage.
• Loop-back (review → implement on CHANGES): no /clear (stay in context to iterate).
• Terminal (ship): no /sdd successor — PR link + «merge is your call».
• Utility (classify-size / glossary / decide-adr / roadmap): «resume your stage», /clear optional.

Changes

• New skills/_shared/handoff.md — the format, the four variants, a canonical stage→review-files→next sequence table, the discipline.
• All 16 skills — final protocol step now emits the handoff block (pointer + its own next command).
• README — the handoff convention in "Start here" + handoff in the _shared list.
• Manifests → 1.8.1.

Verification

• python3 scripts/validate_plugin.py → 177 checks pass; manifests agree on 1.8.1.
• All 16 skills reference the block; 18 handoff.md links resolve; the block shape is canonical to handoff.md only (no skill hard-codes it).

🤖 Generated with Claude Code

[genkovich]

Second commit a4ba697 — config established early, not surfaced late (two reconciliations you flagged while dogfooding):

• .size is now established by specify at the backbone start (classify via the shared size-matrix + write it if absent), so design…plan-tests read a real size instead of silently defaulting to M — the gap that only showed at plan-tests. The handoff block now states the feature_size used and flags a default loudly.
• .claude/sdd.local.md is auto-created early (normally specify, no longer implement-only) with self-documenting defaults — the frontmatter + the «What each key does» body, every key's allowed values explained inline — and .gitignore is patched (.claude/*.local.md already covers it; the repo's own .gitignore has it too).

validate_plugin.py: 177 checks pass; 302 markdown links resolve.